/*
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 * and open the template in the editor.
 */

package homework.demo4;

/**
 *
 * @author Administrator
 */
public class CheckId {
     public static void main(String[] args) {
        String id="4509211991100827201x";
        boolean flag=true;
        if(id.length()!=20){
            flag=false;
        }
        if(!(id.startsWith("45")||id.startsWith("49"))){
            flag=false;            
        }
        String numstr="0123456789x";
        for (int i = 0; i < id.length(); i++) {
            char c=id.charAt(i);
            int temp=numstr.indexOf(c);
            if(temp<0){
                flag=false;
                break;               
            }
        }
            if(flag){
                System.out.println("是合法的身份证号");
            }
            else{
                System.out.println("不是合法的身份证号");
            }
        }
    }

